As wireless communication systems are developing, there are a diversity of types of terminal devices, and types of services, and the following demands may coexist: saving power of a terminal device, saving network resource, and satisfying the various types of services. In order to satisfy, for a terminal device, the demands of saving power and rapid data transmission, the terminal device may be in an inactive state.
An inactive terminal device (i.e., a terminal device in an inactive state) is still connected with a core network, but does not perform any conventional operations in an air-interface connected state, e.g., a handover, uplink timing updating, radio link monitoring, etc., and is not allocated any terminal identifier (e.g., a Cell-Radio Network Temporary Identifier (C-RNTI)) to be used directly for air-interface transmission, thus the inactive terminal device cannot perform air-interface scheduled transmission directly. The inactive terminal device supports rapid data transmission. The rapid data transmission refers to that data are transmitted between the terminal device and a base station in one or two instances of transmission.
In the existing wireless communication systems, data can be transmitted securely between a terminal device and a base station only after the security of the terminal device is activated. The security of the terminal device is activated in a “three-handshake” mechanism, that is, messages shall be exchanged between the terminal device and the base station for three times, and the security of the terminal device can be activated only after all the messages are exchanged successfully for three times. The inactive terminal device shall support rapid data transmission, “three handshakes” may not be guaranteed while data are being transmitted, so data cannot be transmitted securely between the inactive terminal device and the base station in the security mechanism in the existing wireless communication systems.
In summary, it is highly desirable to provide a data transmission solution so as to transmit data securely between an inactive terminal device and a base station.